pub fn max_heapify(mut arr:Vec<i32>, i:i32)-> Vec<i32>{
    let l = if i== 0 {0} else {i-1};
    let r = if i== arr.len()-1 {arr.len()-1} else {i+1};
    let largest = if l<=arr.len()-1 && arr(l)> arr(i) {
        l
    } else{
        r
    };
    if r<= arr.len()-1 && arr(r)> arr(largest)
    if largest != i
        arr.swap(i,l)
        max_heapify(arr, largest)
}

pub fn heapsort(mut arr:Vec<i32>)-> Vec<i32>{
    println!("hello world");
    arr
}
